Heating apparatus



Nov. 5, 1946. G. 1'. wArr I 2,410,537

HEATING APPARATUS med nov. 26, 194s 2 sheets-snm 1 A Him Nov. 5, 1946.

G. T.-wArr HEATING APPARATUS Filed Nov. 26,. 194s 2 Sheets-Sheet 2 Patented Nov. 5, 1946v HEATING Arr 'ros George T. Wait, Chicago, Ill., assignor to Stewart- Warner Corporation, Chicago, Ill.; a corporation of Virginia Application November 26, 1943, Serial No. 511,767'

y scams. (ci. 12s-nt) My invention relates generally to heating apparatus, and more particularly to aircraft heating systems employing a ram and a blower to secure liow of the air for combustion or ventilating air, or both.

Heating systems for aircraft may be conveniently supplied with air under pressure by use of a scoop or ram projecting beyond the skin of the aircraft, but under certain circumstances the ram or scoop does not supply sucient pr'essure to secure satisfactory operation of the heater. For example, when the airplane is on the ground being warmed up, it is frequently desirable to heat the 4cabin preliminary to` take` oi, and unless the scoop or ram is advantageous-l ly located with respect to the propeller slip stream, the ram or scoop will be ineffective to supply air under pressure for operation of the heater. Furthermore, even when in ilight, the ram or scoop may not provide adequate air pressure, as, for example, in the execution `of a dive by a dive' bomber, and` it is therefore desirable to provide some auxiliary means for supplying air under pressure for heater operation at such times that the ram or scoop pressure is insufcient.

It is thus an object of my invention to provide an improved aircraft heating system in which is incorporated means for automatically supplying air under pressure for heater operation by means of a blower whenever the ram or scoop pressure is insufficient for satisfactory heater operation.

A further object is to provide an improved switch operating mechanism, operable inl 11esponse to .the difference in pressure between the air entering the ram or scoop and that supplied by the blower.

Other objects willappear from the following description, reference being had to the accompanying drawings, in which Fig. 1 is a diagrammatic elevational View, partly in section, showing an aircraft heating system embodying the invention;

Fig. 2 is a sectional View of the switch operating mechanism, taken generally on the line 2 2 of Fig. 4;

Fig. 3 is a horizontal sectional view taken lon the line 3-3 of Fig. 4; and

Fig. 4 is a side elevational view with portions` of the valve body and conduit broken away to show the internal construction.

The invention may be utilized in heating systems in which two separatefblowers driven by a common motor are utilized, respectively, to supply air for combustion and for ventilation, in

, 2 which two separate motor driven blowers are provided respectively for these purposes, or in which a single motor driven blower is utilized for supplying-both the Ventilating air andthe air for combustion. A system of the latter type is diagrammatically illustrated in Fig. 1 as coniprising a blower it driven by a motor l2 supplying combustion air and Ventilating air to a housing it secured tothe inlet endvof a heater I6. An air ram or scoop lli, projecting through the airplane skin i9 into the airstream, is connected to the housing it by a conduit 20. v

As best shown in Figs. 2, 3, and li, the conduit is connected to the housing it by a coupling section 22, the end of which projects a substantial distance into the housing it, and forms a valve seat 291. The casing of the blower l@ is similarly connected ,to a. coupling section 2t,

which projects into the housing l@ a substantialv distance and the inner end of which is cut at an angle to provide a sloping valve seat 28. A damper or flap valve 3U is secured to a square shaft 32, the ends of which are cylindrical and project through bearings 3ft and 35. The latter may be welded or otherwise suitably secured to thehousing lll. An arm 36 is peened to a sleeve 38 which is pinned to the shaft 3d. The free end of the arm 36 has a sidewardly projecting pin tt cooperable with a leaf spring actuator 42 forming part of a microswitch M of conventional construction. Y j

The switch M operates in such manner that it is open whenthe arm 36 is in its upright position, as shown in Fig. 4, and closed when the arm swings about 45 eounterclockwise from this position. In Fig. 1, for purposes of simplicity, it is assumed thatthemicro-switch is directly in the energizing circuit for the blower motor I2. although in actual practice the micro-switch d will usually operate a relay in the energizing `circuit for the motor l2. The micro-switch @d is secured .to a bracket which may be welded or otherwise suitably secured tothe coupling section 2S. v

If the apparatus is to be mounted in a horizontalposition, as.illustrated, gravity may be relied upon toA swing the iiap valve 30 from its full line position to its dotted line position (Fig, 4), although ordinarily the force of gravity will preferably be supplemented by a light spring. the tension of which may be adjusted to secure proper operation of the iiap valve in the particular position in which the apparatus is installed.

In operation, witha the plane'on the ground and the scoop I` providing insufficient pressure for lthe operation of the heater, the ilap valve 30 will occurs, the pressure in the scoop I8 will build up to a value suicient to swing the flap valve 30 from itsl dotted line position to its full line position (Fig. 4), whereupon the pin 40 on the arm 3B will engage the leaf spring 42, and through the latter operate the micro-switch 44 to open the energizing circuit for the motor l2. The heater will then continue in operation, utilizing the air supplied by the scoop, until such .time as the airplane reduces its speed, as in a dive bombing dive. Under these circumstances, the dynamic air pressure available from the scoop ,I8 may be insufficient to maintain the ilap valve 30 in its full line position, and the valve will swing downwardly under the influence of gravity with or without the additional pull of a spring, thereby moving the pin 40 away from the leaf spring 42 and permitting the operation of the micro-switch 44 .to eiect reenergization of the blower motor I2. v l

Due to the fact that the seat 28 for :the valve 30 is at an angle, the air flowing through the housing i4 from the scoop I8 will tend to hold the valve against this seat and prevent fluttering thereof. Reverse flow through the coupling Vsection 26 to the blower Ill is thus precluded.

As previously indicated, the housing I4 and 4 movable member comprising a valve mounted in the housing in position to close the connection between the scoop or ram and said housing at the other limit of its range of movement.

3. In the combination dened in claim 1, said control device' being actuated by said movable member to stop the blower when the pressure of the air owing from the scoop or ram rises above a predetermined value and said member responds to said pressure by movement toward said one limit of itsrange and beyond a predetermined point.

4. In the combination dened in claim 1, said movable member comprising a valve mounted in the housing in position to close the connection between the blower and said housing at said one limit of its movement and being moved toward said limit by the pressure from the scoop or ram when said pressure rises above a predetermined value.

5. In an aircraft kheating system having a heater of the sealed combustion type, and having a scoop or ram and a blower for supplying air to the heater, the combination of a housing connected to said scoopv or ram, to the outlet of said blower, and to the inlet of said heater, a valve member pivotally pendant in said housing for swinging movement through a. limited range therein, said member closing the connection bemechanism associated therewith may be utilized' in the combustion air supplyline and be utilized to -control the operation of a single blower supplying both combustion and Ventilating air, or to control the operation of two blowers respectively supplying combustion air and Ventilating air. It is desirable, in order to prevent overheating of the heater, tq') cause the Ventilating airto be supplied by the blowerinstead of the ram o r scoop whenever the combustion air is supplied by its blower.

` While I have shown and described a particular embodiment of my invention, it will be apparent the heater, the combination of a housing connected to said scoop or ram, to the outlet of said blower and to the inlet of said heater, a member having a range of movement and movable toward one limit of its range in response to the pressure -of the air owing from'said scoop or ram and yieldably biased in .the opposite direction,l and a and operative .to stop and start the blower, said control device being so actuated for starting. the blower when the `pressure from the scoop or ram falls below a predeterminedvalue and permits said member to move in said opposite direction.

' 2. In the combination dened in claim 1, said upper limit of its range and being tween the scoop or ram and the housing at the lower limit of its range and closing the connection between the blower and the housing at the swingable from said lower limit toward said upper limit by the dynamic pressure of air iiowing from the s coop or ram, and a control. device actuated by said valve member and operative to stop and start the blower, said control device being so actuated for starting the blower by movement of said valve member below a predetermined position in its range and being actuated for stopping the blower by movement of said valve member above a predetermined position in said range.

6. In the combination defined in claim 5, said valve member extending obliquely into the path of air flowing from the scoop or ram to the heater when said valve is positioned at its upper limit -control device actuated by saidmovable member closing the connection from the blower to the housing.

7. In an aircraft heating system having -a heater of the sealed combustion type and having a scoop or ram and a blower for supplying air to the heater, the combination of a housing having an outlet connected to the heater and having a pair of inlets, one connected to the outlet of the blower and the other connected to the scoop or ram, valve means mounted in said housing and movable to one position closing the inlet from the blower and to another position closing the inlet from the ram, said valve being 'responsive' to the pressure of the air from the ram and movable thereby to its position for closing the inlet from the blower, a motor connected to drive said blower, a control switch for said motor, means biasing said switch to closed position and means operable by the movement of the valve means to open said switch when the ram pressure rises above a predetermined value.

8. In an aircraft heating system having a heater of the sealed combustion type, and having a scoop or ram and a blower for supplying air to the heater, the combination of a housing having an outlet connected to the heater and having a pair of inlets, one connected to the outlet of the blower and the other connected to the scoop or ram, a motor connected to drive said blower, a the ram and movable thereby toits position for control switch for said motor, and means to aoclosing theu inlet from the blower, said valve optuate said switch including valve means mounted erating to open said switch whenv the valve in said housing and movable to one position clos reaches a predetermined position in said moveing the inlet from the blower and to another posi- 6 ment to close the inlet from the blower.

tion closing the inlet from the ram, said valve being responsive to the pressure of the air from GEORGE T; WAIT.

Disclaimer 2,410,537.George T. `Wait, Chicago, Ill. HEATING APPARATUS. Patent dated Nov. 5, 1946. Disclaimer led July 8, 1948, by the assignee, StewartQWarner Corporation. Hereby enters this disclaimer to claims 1 and 3 in said specification.

[Oficial Gazette August 17', 1948.] 

